main.go

// Copyright 2021 The Prometheus Authors
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package main

import (
	"fmt"
	"net/http"
	"os"

	"github.com/alecthomas/kingpin/v2"
	"github.com/prometheus/client_golang/prometheus"
	promcollectors "github.com/prometheus/client_golang/prometheus/collectors"
	versioncollector "github.com/prometheus/client_golang/prometheus/collectors/version"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	"github.com/prometheus/common/promslog"
	"github.com/prometheus/common/promslog/flag"
	"github.com/prometheus/common/version"
	"github.com/prometheus/exporter-toolkit/web"
	"github.com/prometheus/exporter-toolkit/web/kingpinflag"

	"github.com/prometheus-community/ecs_exporter/ecscollector"
	"github.com/prometheus-community/ecs_exporter/ecsmetadata"
)

const exporter = "ecs_exporter"

func main() {
	promslogConfig := &promslog.Config{}
	flag.AddFlags(kingpin.CommandLine, promslogConfig)

	metricsPath := kingpin.Flag("web.telemetry-path", "Path under which to expose metrics.").Default("/metrics").String()
	disableExporterMetrics := kingpin.Flag(
		"web.disable-exporter-metrics",
		"Exclude metrics about the exporter itself (promhttp_*, process_*, go_*).",
	).Bool()
	toolkitFlags := kingpinflag.AddFlags(kingpin.CommandLine, ":9779")

	registry := prometheus.NewRegistry()
	registry.MustRegister(versioncollector.NewCollector(exporter))
	kingpin.Version(version.Print(exporter))

	kingpin.HelpFlag.Short('h')
	kingpin.Parse()

	logger := promslog.New(promslogConfig)

	client, err := ecsmetadata.NewClientFromEnvironment()
	if err != nil {
		logger.Error("Error creating client", "error", err)
		os.Exit(1)
	}
	registry.MustRegister(ecscollector.NewCollector(client, logger))

	handler := promhttp.HandlerFor(registry, promhttp.HandlerOpts{})
	if !*disableExporterMetrics {
		registry.MustRegister(
			promcollectors.NewProcessCollector(promcollectors.ProcessCollectorOpts{}),
			promcollectors.NewGoCollector(),
		)
		handler = promhttp.InstrumentMetricHandler(registry, handler)
	}

	http.Handle(*metricsPath, handler)
	if *metricsPath != "/" && *metricsPath != "" {
		landingConfig := web.LandingConfig{
			Name:        exporter,
			Description: "Prometheus Exporter for ECS",
			Version:     version.Info(),
			Links: []web.LandingLinks{
				{
					Address: *metricsPath,
					Text:    "Metrics",
				},
			},
		}
		landingPage, err := web.NewLandingPage(landingConfig)
		if err != nil {
			logger.Error("Error creating landing page", "err", err)
			os.Exit(1)
		}
		http.Handle("/", landingPage)
	}

	http.HandleFunc("/health", func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusOK)
		fmt.Fprint(w, "ok")
	})

	srv := &http.Server{}
	if err := web.ListenAndServe(srv, toolkitFlags, logger); err != nil {
		logger.Error("Error starting server", "err", err)
		os.Exit(1)
	}

}